Biology subjects

Herschend, J.

Publications and source records attributed to Herschend, J..

3 recordsLinked to original sources

bioRxiv2023

Evolution of genotypic and phenotypic diversity in multispecies biofilms

Bacterial fitness and adaptability in microbial communities are influenced by interspecies interactions and spatial organization. This study investigated how these factors shape the evolutionary dynamics of Bacillus thuringiensis. A distinct phenotypic variant of B. thuringiensis emerged consistently under both planktonic and biofilm conditions, as well as in monospecies and mixed-species settings, but was strongly selected in biofilms and during coexistence with Pseudomonas defluvii and/ or Pseudomonas brenneri. Compared to its ancestor, the variant exhibited shorter generation times, reduced sporulation, auto-aggregation, and lower biomass in mixed-species biofilms. Mutations in the spo0A regulator, which controls sporulation and biofilm matrix production, were identified in all variants. Proteomics revealed a reduction in TasA, a key matrix protein, in the variant but increased levels in co-culture with P. brenneri. These findings highlight how interspecies interactions drive B. thuringiensis diversification, promoting traits like reduced matrix production and species coexistence, with implications for microbial consortia applications in agriculture and biopesticides.

microbiology↗

bioRxiv2019

Construction of simplified microbial consortia to degrade recalcitrant materials based on enrichment and dilution-to-extinction cultures

The capacity of microbes degrading recalcitrant materials has been extensively explored from environmental remediation to industrial applications. Although significant achievements were obtained with single strains, focus is now going toward the use of microbial consortia because of advantages in terms of functional stability and efficiency. While consortia assembly attempts were made from several known single strains, another approach consists in obtaining consortia from complex environmental microbial communities in search for novel microbial species, genes and functions. However, assembling efficient microbial consortia from complex environmental communities is far from trivial due to large diversity and biotic interactions at play. Here we propose a strategy containing enrichment and dilution-to-extinction cultures to construct simplified microbial consortia (SMC) for keratinous waste management, from complex environmental communities. Gradual dilutions were performed from a keratinolytic microbial consortium, and dilution 10-9 was selected to construct a SMC library. Further compositional analysis and keratinolytic activity assays demonstrated that microbial consortia were successfully simplified, without impacting their biodegradation capabilities. These SMC possess promising potential for efficient keratinous valorization. More importantly, this reasoning and methodology could be transferred to other topics involving screening for simplified communities for biodegradation, thus considerably broadening its application scope.\n\nImportanceMicrobial consortia have got more and more attention and extensive applications due to their potential advantages. However, a high diversity of microbes is likely to hide uncontrollable risks in practice specific to novel strains and complicated interaction networks. Exploring a convenient and efficient way to construct simplified microbial consortia is able to broaden the applied scope of microbes. This study presents the approach based on enrichment and dilution-to-extinction cultures, which gain abundance microbial consortia including some without losing efficiency from the enriched functional microbial community. The microbial interactions at the strain level were evaluated by using compositional identification and correlation analysis, which contribute to revealing the roles of microbes in the degradation process of recalcitrant materials. Our findings provide a systematic scheme to achieve optimizing microbial consortia for biodegradation from an environmental sample, could be readily applied to a range of recalcitrant materials management from environmental remediation to industrial applications.

microbiology↗

bioRxiv2018

In vitro community synergy between bacterial soil isolates can be facilitated by pH stabilisation of the environment

Composition and development of naturally occurring microbial communities is defined by a complex interplay between the community and the surrounding environment and by interactions between community members. Intriguingly, these interactions can in some cases cause community synergies where the community is able to outperform it single species constituents. However, the underlying mechanisms driving community interactions are often unknown and difficult to identify due to high community complexity. Here we show how pH stabilisation of the environment through the metabolic activity of specific community members acts as a positive inter-species interaction driving in vitro community synergy in a model consortium of four co-isolated soil bacteria: Microbacterium oxydans, Xanthomonas retroflexus, Stenotrophomonas rhizophila and Paenibacillus amylolyticus. Using micro-sensor pH measurements to show how individual species change the local pH micro-environment, and how co-cultivation leads to a stabilised pH regime over time. Specifically, in vitro acid production from Paenibacillus amylolyticus and alkali production primarily from Xanthomonas retroflexus lead to an overall pH stabilisation of the local environment over time, which in turn resulted in enhanced community growth. This specific type of interspecies interaction was found to be highly dependent on media type and media concentration, however similar pH drift from the individual species could be observed across media variants.\n\nImportanceWe show that in vitro metabolic activity of individual members of a synthetic, co- isolated model community presenting community synergistic growth arises through the inter-species interaction of pH stabilization of the community micro-environment. The observed inter-species interaction is highly media specific and most pronounced under high nutrient availability. This adds to the growing diversity of identified community interactions leading to enhanced community growth.

microbiology↗